Monday, June 06, 2016

Mutant Human-pigs Created for Organs in U.S.

American researchers are using human stem cells and modified pig embryos to create a new life form dubbed "chimera" in order to cultivate a variety of human organs suitable for subsequent transplantation to humans.

“Our hope is that this pig embryo will develop normally but the pancreas will be made almost exclusively out of human cells and could be compatible for transplantation.”-- Pablo J. Ross, Ph.D. Assistant Professor, University of California, Davis

“The organ would be an exact genetic copy of your liver but a much younger and healthier version . . . With every organ we will look at what's happening in the [pig's] brain and if we find that it's too human like, then we won't let those foetuses be born.”-- Walter Low, Department of Neurosurgery, University of Minnesota

“Chimeras will be seen to be what they are which is a saviour, given that they will provide, life-saving, sustaining organs for our patients.”-- Scott Fahrenkrug, Recombinetics (a Minnesota-based company)

The team from University of California, Davis says they should look and behave like normal pigs except that one organ will be composed of human cells.

Creating the chimeric embryos takes two stages. First, a technique known as CRISPR gene editing is used to remove DNA from a newly fertilised pig embryo that would enable the resulting foetus to grow a pancreas.

This creates a genetic "niche" or void. Then, human induced pluripotent (iPS) stem cells are injected into the embryo. The iPS cells were derived from adult cells and "dialled back" to become stem cells capable of developing into any tissue in the body.

But the work is controversial. . . . The main concern is that the human cells might migrate to the developing pig's brain and make it, in some way, more human.

It was reported earlier this year that scientists had begun attempts to create the embryos, but there has been opposition from authorities. In September last year, the US National Institutes of Health said it would not back research into “chimeras” until it knew more about the implications.

Concerns have been raised about whether the transplantation of an organ from an animal into a human could risk introducing animal viruses into a patient. Researchers from Harvard Medical School, however, revealed last year that it was possible to use gene-editing technology to inactivate more than 60 retrovirus genes in pigs in a step towards such organ transplantation.

Prof George Church, who has led similar research into the possible use of chimeras, [said] “It opens up the possibility of not just transplantation from pigs to humans but the whole idea that a pig organ is perfectible.

“Gene editing could ensure the organs are very clean, available on demand and healthy, so they could be superior to human donor organs.”